The present invention relates to methods for modifying synthetic surfaces to support the growth, migration and attachment of epithelial, endothelial and other cell types both in vitro and in vivo, as well as the modified surfaces themselves. More specifically, the invention relates to methods for modifying the tissue-contacting surfaces of synthetic, implantable prosthetic devices, especially contact lenses, to better support the growth, migration and attachment of epithelial cells. The invention also relates to the prosthetic devices themselves.
There are a number of prosthetic devices which necessarily or desirably can be implanted either completely or partially beneath epithelial tissues. It is to be understood that reference to "epithelial" tissues herein includes epidermal tissue as well as other epithelial tissues. Implantation beneath the epithelium may be done for purposes of fixation of the device relative to other tissues and/or for cosmetic purposes. Examples of implanted prostheses include dental prostheses such as artificial teeth and bridgework, hearing aids, dermal implants, vascular access devices, such as those associated with hyperalimentation, colostomy devices and prosthetic corneas. While the present invention will be described with reference to prosthetic corneas for subepithelial implantation, and with specific reference to an epikeratophakia lens, it will be readily understood that the invention is not so limited.
The permanent implantation in the eye of a synthetic epikeratophakia lens has major advantages over operations such as radial keratotomy to correct severe vision problems. Implanting the synthetic epikeratophakia lens does not involve compromising the anterior chamber, for example. In the implantation procedure, the epithelial layer is removed via a trephine and scrape, the wound is undermined and the lens is tucked into place. Reepithelialization of the lens is expected to result in a permanent correction of vision for the patient. By "reepithelialization" it is meant not only the growth and migration (or `spreading`) of epithelial cells, but also the attachment and stabilization of these cells.
Reepithelialization of the implant is important for a variety of reasons. For example, reepithelialization is very important in order to ensure long term anchorage of an implant. The layer of new cells also acts as a barrier to prevent tear-born and other materials from depositing on the lens surface. Unfortunately, many materials which exhibit beneficial properties when formed into prosthetic devices (such as stability and lack of immune response) do not adequately support the growth, migration and attachment of epithelial cells.
It should be noted at the outset that the methods and modified synthetic surfaces of the present invention also are useful for the in vitro growth of epithelial cells. Epithelial cells grown in the laboratory upon surfaces modified according to the present invention exhibit growth, migration and attachment quite similar to the in vivo growth pattern of epithelial cells.
Thus, there is a need for a procedure whereby tissue-contacting surfaces of prosthetic devices or implants are modified in order to better support the growth, migration and attachment of epithelial cells. There is also a need for a procedure whereby surfaces of tissue culture plates and other laboratory equipment are modified to better support epithelial cells.